The present invention relates to aerial vehicles. In particular, the present invention relates to a vertical takeoff and landing (VTOL) unmanned aerial vehicle having a pair of counter-rotating, variable-pitch propeller blades for providing reversible thrust to allow for distinct hovering and forward flight modes of operation, a toroidal duct that acts as a lifting surface in forward flight mode, and canard wings positioned in front of a leading edge of the duct.
There has been a recent increased emphasis on the use of unmanned aerial vehicles (UAVs) for performing, various activities in both civilian and military situations where the use of manned flight vehicles is not appropriate and/or feasible. Such missions include surveillance, reconnaissance, target acquisition and/or designation, data acquisition, communications relay, decoy, jamming, harassment, ordnance delivery, or supply flights. This increased emphasis on the role of UAVs in today""s (and tomorrow""s) society has led to many advancements in both airframe design and propulsion systems for UAVs.
There are generally three types of UAV configurations: a fixed-wing type configuration (a fuselage with wings and horizontally mounted engines for translational flight), helicopter type configuration (a fuselage with a rotor mounted above which provides lift and thrust), and ducted type configuration (a fuselage with a ducted rotor system which provides translational flight, as well as vertical take-off and landing capabilities). A wing-type UAV provides several benefits over a helicopter or ducted type UAV. First, and foremost, is the ability of a winged UAV to travel at considerably greater speeds and for longer distances than a conventional helicopter or ducted type UAV. Also, a winged UAV can typically carry a larger mission payload and/or fuel supply than a helicopter or ducted type UAV. As such, fixed-wing UAVs are generally better suited than helicopter or ducted type UAVs for certain mission profiles involving endurance, distance, higher speed and load capability.
Winged UAVs, however, generally have deficiencies that limit their utility for unmanned tactical reconnaissance. For example, winged UAVs require forward motion to maintain lift and, therefore, are not capable of hovering over a fixed spatial point, which may be desirable in some situations. Also, winged UAVs cannot take-off and land vertically, but may require elaborate launch and retrieval equipment.
Helicopter UAVs can hover over a fixed spatial point and takeoff and land vertically but have limitations when operating in confined areas due to the exposed rotors rotating above the fuselage. Also, helicopter UAVs tend to have a high center-of-gravity (CG) and therefore have limited ability when landing on sloped surfaces or pitching ship decks. A high CG aircraft tends to roll over when landing on steep slopes.
The ability of a ducted rotor-type UAVs to take-off and land vertically, hover for extended periods of time over a fixed spatial point, operate in confined areas, and land on sloped surfaces if desired, makes a ducted rotor-type UAV ideally suited for real time tactical reconnaissance, target acquisition, surveillance, and ordnance delivery missions for front line tactical units. However, many ducted rotor-type UAVs do not have the ability to transition to high speed forward flight.
What is still desired is an improved unmanned aerial vehicle that can take-off and land vertically, hover for extended periods of time over a fixed spatial point, operate in confined areas, and land on sloped surfaces if desired. Preferably, the improved vehicle will also have the ability to transition between a hover and high speed forward flight.
The present invention generally provides an aerial vehicle including a toroidal fuselage having a longitudinal axis, and a duct extending along the longitudinal axis between a leading edge and a trailing edge of the fuselage, first and second counter-rotating, variable pitch rotor assemblies coaxially mounted within the duct of the fuselage, and at least one canard wing secured to the toroidal fuselage and having a leading edge positioned out of the duct of the fuselage and axially forward of the leading edge of the fuselage, wherein at least a portion of the canard wing comprises a control surface having a variable angle of attack.
The aerial vehicle can take-off and land vertically, hover for extended periods of time over a fixed spatial point, operate in confined areas, and land on sloped surfaces if desired. The aerial vehicle of the present invention also has the ability to transition between a hover and high speed forward flight.
The present invention also provides an aerial vehicle including a toroidal fuselage having a longitudinal axis, and a duct extending along the longitudinal axis, a hollow propeller shaft coaxially extending along the axis and within the duct, and first and second rotor assemblies coaxially mounted on the propeller shaft within the duct. Each rotor assembly includes a hub mounted on the propeller shaft for rotation about the axis, and at least two propeller blades extending radially outwardly from the hub. Each propeller blade includes an axis extending substantially normal with respect to the axis of the duct, and the propeller blades are rotatably about the blade axes.
Each rotor assembly also includes a coupling assembly received on the propeller shaft and movable with respect to the propeller shaft parallel with the axis of the fuselage, and linkages pivotally connected between the coupling assembly and the propeller blades so that movement of the coupling assembly on the propeller shaft causes rotation of the propeller blades about the propeller axes. A rod is received within the hollow propeller shaft, and is movable with respect to the propeller shaft parallel with the axis of the duct. The rod is connected to the coupling assemblies so that movement of the rod within the propeller shaft causes movement of the coupling assembly on the propeller shaft.
The foregoing and other features and advantages of the present invention will become more apparent in light of the following detailed description of the preferred embodiments thereof, as illustrated in the accompanying figures. As will be realized, the invention is capable of modifications in various respects, all without departing from the invention. Accordingly, the drawings and the description are to be regarded as illustrative in nature, and not as restrictive.